IOWA CITY, Iowa — A conservative group that has brought a string of potential presidential candidates to Iowa to lecture about the need to reduce government spending owes some of its past success to generous federal grants, which it has since rejected amid charges of hypocrisy.

The Family Leader has organized multicity forums for Reps. Michele Bachmann and Ron Paul, former Minnesota Gov. Tim Pawlenty and former Sen. Rick Santorum. Each has called for reining in federal spending and talked about family values.

The same group received more than half of its funding from federal grants over a five-year period when it operated under a different structure as The Iowa Family Policy Center. The group was among those that benefited from former President George Bush’s faith-based initiative, which made it easier for social and religious organizations involved in community work to win federal funding.

The organization defends taking the grants, the bulk of which helped provide marriage mentoring for couples, but decided last year to turn down the final $550,000 in grant money and operate free of government involvement. In all, the group had accepted more than $3 million in federal grants since 2004...